1. Field of the Invention
This invention relates generally to a brake booster for automobiles, and more particular, to a vacuum brake booster which includes a power piston, a push rod connected to a brake pedal, an output rod operatively connected to a brake master cylinder piston, a reaction plate interposed between the push rod and a power piston and a valve mechanism for actuating the power piston.
2. Description of the Prior Art
Conventionally, the relationship between a cylindrical member and a reaction plate member is as shown in FIG. 3, wherein a gap 35 is formed between a reaction disc plate 29' and a cylindrical member 27' of a brake booster assembly. Under this condition, when the brake pedal is depressed for brake operation, the initial stage of the operation is ineffective until the reaction disc plate 29' is deformed to completely occupy gap 35.
It has therefore been necessary to provide a rounded portion 29'a at opposite ends of the reaction disc plate 29' in order to avoid any difficulty with improper reverse insertion of the plate 29' into cylindrical portion 26' of power piston 5'. It has also been necessary to provide a sufficient length (l) of the cylindrical member 27' in order to provide sufficient relative movement between the power piston 5' and the member 27'.